Author/Editor		Dolenšek, Janez
Title		Simulacija pljuč, alveolne ventilacije ter njenega uravnavanja z negativno povratno zvezo
Type		monografija
Place		Ljubljana
Publisher		Univerza v Ljubljani, Medicinska fakulteta
Publication year		2005
Volume		str. 77
Language		slo
Abstract		In the medical research and in teaching various models are used. They very often use digital (mathematical) modelling (simulation) of various physiological processes. However, mathematical modelling is demanding and therefore not easily accessible. Therefore in this investigation another approach is used: analogue simulation. By using the Electronics Workbench software an electronic equivalent circuit is designed, simulating the lung and its ventilation. The circuit is upgraded by including a negative feedback to control alveolar ventilation. Simulations were performed under the conditions in which the negative feedback loop was either open or closed. In the first experimental condition, when negative feedback was not operative, only the immediate consequences of the disturbance could be observed. In the second experimental condition, when negative feedback was operative, complex homeostatic phenomena could be observed. The latter - in principle - minimizes the consequences of the initial disturbance. Under the conditions in which the negative feedback loop was either open or closed, three different types of disturbance were studied: i) increased production of CO2, ii) temporary apnea and iii) increased aiarway resistance (bronchoconstriction). The heterogeneous lung model was used to simulate bronchoconstriction in the entire lung. The heterogeneous lung model was used to simulate bronchoconstriction in only one section, comprising a half of the lung. Increased production of CO2 resulted in an increase of tidal volume and in increased arterial pCO2. The latter was highly dependent on the response of the negative feedback. Temporary apnea resulted in a temporary increase in pCO2. When, in the feedback loop, the delay in signal transfer was relatively large, temporary apnea induced the periodic, i.e. Cheyne-Stokes breathing. Bronchoconstriction which affected the whole lung resulted in a decrease in the tidal volume. (Abstract truncated at 2000 characters).
Descriptors		ELECTRONICS, MEDICAL LUNG PULMONARY VENTILATION HYPERCAPNIA APNEA AIRWAY RESISTANCE BRONCHOCONSTRICTION TIDAL VOLUME MODELS, BIOLOGICAL